Ah, I don't know if that's true, but on my singlespeed conversion (a 1982 Fuji), I have 27" wheels. And I love them. The ride is comfortable and quick, and you feel up there. I understand that 700c has forever supplanted them, but what is the downside?

I have a set of 27" Wobler Super Champion rims laced to some Specialized (Suntour) 36 hole Sealed hubs. They ride very nicely. The only issue I had so far was that I broke a spoke in the rear wheel and the closest shop did not have any replacements long enough to fit the wheel. I have never had a problem w/ tire selection though. Schwalbe still makes a number of offereings in 27 inch as do others. I run them at 90 psi and they work great.

I have an old 1984 Trek 720 that still has the original 27" wheels and 1 1/4" tires. Rides pretty nice and just as fast as my road bike with 700 x 23. Or at least I can't seem to tell a difference in speed. The wider tires of the trek are a little more plush though.

When it comes time to replace the wheels on the trek I will likely go with 700 x 32 or so. Manly for the tire selection. I will have to replace the brakes though as the current cantilevers will not work with 700 wheels, I tried.

Bolo: when you tried the 700c, was it just as simple as popping a 700 into the fork? Did you actually try to move the brake pads down, or did you just eyeball it?
I'm thinking of converting the singlespeed to a fixed, and there are far more 700c track wheels available. (In fact, I think Harris Cyclery is the only shop to offer a 27" fixed wheel.) I won't need a rear brake anymore, so that won't be a problem. But how off would it be to run a 700c rear and a 27" front?

my local lbs had SS wheels in 27" for $65 all day. And i've had no problem running them at 100 psi, or finding tires. in fact they're usually easy to find for cheap as well. If you have your sights set on a specific tire, they might not make it but to say that 27 wheels and tires are elusive is altogether incorrect.

Bolo: when you tried the 700c, was it just as simple as popping a 700 into the fork? Did you actually try to move the brake pads down, or did you just eyeball it?
I'm thinking of converting the singlespeed to a fixed, and there are far more 700c track wheels available. (In fact, I think Harris Cyclery is the only shop to offer a 27" fixed wheel.) I won't need a rear brake anymore, so that won't be a problem. But how off would it be to run a 700c rear and a 27" front?

Thee is no real up and down adjust of the cantilever brakes I have due to the position of them. I took the 700c wheel off of my newer road bike and put it on the old trek. The brakes did not line up where they needed to be. Although I admit to not spending alot of time on this.

Switching to the caliper style brakes found on most new road bikes will likely work, may need long reach, but may not.

I have 27" wheels on my SS beater. My old touring bike took 27" wheels, too. There's no problem finding tires, unless you want really big or really skinny ones. I don't really like them any better or worse than 700C wheels - they're bigger, yes, but only marginally. It doesn't end up amounting to much.